A Novel Approach to Improving the Quality of Bittern-Solidified Tofu by W/O Controlled-Release Coagulant. 2: Using the Improved Coagulant in Tofu Processing and Product Evaluation

To improve the quality and yield of traditional firm tofu prepared with bittern as coagulant, water-in-oil (W/O) emulsions with bittern solution as the aqueous phase, where the ratio of the bittern solution to the oil phase was 1:1.5 or 1:1 (w/w), and an emulsifier at a concentration of 0.8 or 1.0 wt.% were prepared. The parameters water content, water-holding capacity, yield, texture, and microstructure of the tofu were tested. The results indicated that the bittern W/O emulsions provided satisfactory controlled-release application potential. The use of the W/O emulsions significantly improved tofu’s water content, and the product remained moist for at least 24 h. Moreover, emulsified bittern increased the yield and made the gel network more homogenous and compact compared with the control. As expected, emulsions with an emulsifier concentration of 1.0 wt.% showed slightly better controlled-release capacity than those with 0.8 wt.%.     

PV1 Protein from Plasmodium falciparum Exhibits Chaperone-Like Functions and Cooperates with Hsp100s

Plasmodium falciparum parasitophorous vacuolar protein 1 (PfPV1), a protein unique to malaria parasites, is localized in the parasitophorous vacuolar (PV) and is essential for parasite growth. Previous studies suggested that PfPV1 cooperates with the Plasmodium translocon of exported proteins (PTEX) complex to export various proteins from the PV. However, the structure and function of PfPV1 have not been determined in detail. In this study, we undertook the expression, purification, and characterization of PfPV1. The tetramer appears to be the structural unit of PfPV1. The activity of PfPV1 appears to be similar to that of molecular chaperones, and it may interact with various proteins. PfPV1 could substitute CtHsp40 in the CtHsp104, CtHsp70, and CtHsp40 protein disaggregation systems. Based on these results, we propose a model in which PfPV1 captures various PV proteins and delivers them to PTEX through a specific interaction with HSP101.     

酸性电生功能水对鲜榨梨汁品质的影响

以皇冠梨为试材,利用酸性电生功能水对梨块浸泡,考察了酸性电生功能水对鲜榨梨汁品质的影响。结果表明,酸性电生功能水可将鲜榨梨汁中细菌总数降低1.5个对数值左右,并且可将梨汁中多酚氧化酶活性降低50%以上,其护色效果与添加0.1%VC的自来水相当,且梨汁风味接近对照。酸性电生功能水抑制多酚氧化酶的效果与酸性水中有效氯浓度、pH以及梨块与酸性水的比例有关。研究发现当酸性电生功能水理化指标为有效氯浓度100mg/L,pH5.0,料液比1:4时钝酶效果较为理想。     

The effects of natural fermentation on the physical properties of rice flour and the rheological characteristics of rice noodles

The effects of fermentation of whole polished rice grains on the physical properties of rice flour and the rheological characteristics of rice noodles were investigated. Natural fermentation had little effect on the crystalline structure of rice starch, as measured by X‐ray diffraction, but the ratio of the crystalline to the amorphous regions increased. The thermal properties of rice flours were determined using differential scanning calorimetry and a rapid viscosity analyser (RVA). The gelatinization temperature, T_p, and the RVA peak viscosity of rice flour decreased, while the gelatinization enthalpy, ΔH, increased after fermentation. The FTIR spectra of fermented and control rice flours were similar. Fermented rice starch granules had slight superficial corrosion when examined using scanning electron microscopy. Fermentation may thus change the amorphous region of the starch granule as well as the chemical components and thereby modify both physical properties of rice flour and rheological characteristics of rice noodles.     

加工工艺对豆豉抗氧化能力的影响

本文以黄豆为原材料制作豆豉，测定了浸泡、蒸煮、曲霉发酵、加盐后豆豉50％乙醇提取物清除DPPH（2，2-diphenyl-1-picrylhydrazyl hydrate）及ABTS[2，2’-azinobis-（3-ethylbenzthiazoline-6-sulfonicacid）]自由基能力，评价了加工工艺对豆豉抗氧化能力的影响。大豆经过浸泡、蒸煮后，其提取物抗氧化能力变化不大。曲霉发酵过程中，豆豉的抗氧化能力随发酵时间的延长而增大。后发酵过程中，豆豉的抗氧化能力持续增大，盐对豆豉的抗氧化能力有影响，发酵相同时间的豆豉，抗氧化能力随盐含量的增大而下降。     

紫红链霉菌Streptomyces violaceoruber IFO 15732产褐藻胶裂解酶的培养条件优化

对紫红链霉菌(Streptomyces violaceoruber)IFO 15732产褐藻胶裂解酶发酵条件进行了研究。结果表明,以褐藻胶的裂解酶活为指标,该菌株最适发酵条件为:海藻酸钠0.4%、酵母粉0.15%、KH2PO40.1%;MgSO4·7H2O 0.05%(w/v),pH=6.0。最适发酵产酶温度为30℃,培养时间为6d。在最适培养条件下,菌株的最高产酶活力达到57.8U/mL。     

Angiotensin I-converting enzyme inhibitory peptides in douchi,a Chinese traditional fermented soybean product

Douchi, a soybean product originating in China, produces angiotensin I-converting enzyme (ACE) inhibitors with the potential to lower blood pressure. The ACE inhibitory activities of douchi qu pure-cultured by Aspergillus Egyptiacus for 48 h, and 72 h were compared with douchi secondary-fermented for 15 d. The results showed that ACE inhibitory activities were improved following the fermentation. ACE inhibitory activities of 48 h-primary-fermented douchi qu did not change dramatically after preincubation with ACE, but increased greatly after preincubation with gastrointestinal proteases. The results suggest they were pro-drug-type or a mixture of pro-drug-type and inhibitor-type inhibitors. The ACE inhibitors in 48 h-fermented douchi qu were fractionated into four major peaks by gel filtration chromatography on Sephadex G-25. Peak 2, which had the highest activity, had only one peptide, composed of phenylalanine, isoleucine and glycine with a ratio of 1:2:5.     

Isolation and characterisation of a novel angiotensin I‐converting enzyme‐inhibitory peptide derived from douchi,a traditional Chinese fermented soybean food

BACKGROUND: Douchi, a traditional fermented soybean food, has recently attracted a great deal of attention owing to its superior physiological activity. In the present study the angiotensin I‐converting enzyme (ACE)‐inhibitory activity of typical douchi procured from various regions of China was analysed. An ACE‐inhibitory peptide derived from the most potent douchi was also isolated and characterised. The pattern of ACE inhibition and resistance to hydrolysis by gastrointestinal proteases of this peptide are described. RESULTS: ACE‐inhibitory activities were detected in all douchi samples, with IC₅₀ values ranging from 0.204 to 2.011 mg mL^?1. Among the douchi samples, a Mucor‐type douchi exhibited the most potent ACE‐inhibitory activity (IC₅₀ = 0.204 mg mL^?1). A novel ACE‐inhibitory peptide was then isolated from this Mucor‐type douchi using ultrafiltration followed by Sephadex G‐25 column chromatography and reverse phase high‐performance liquid chromatography. The amino acid sequence of the purified peptide was identified by Edman degradation as His‐Leu‐Pro (IC₅₀ = 2.37 µmol L^?1). The peptide is a competitive inhibitor and maintained its inhibitory activity even after incubation with some gastrointestinal proteases. CONCLUSION: The present study shows that peptides derived from soybean fermentation during douchi processing could be the main contributor to the ACE‐inhibitory activity observed. Copyright © 2009 Society of Chemical Industry